The removal or extraction of blood from conscious animals has been utilized to determine the presence of bacteria, hormones, parasites, toxins, as well as the metabolism of drugs and other substances in the animal. Heretofore, the removal of blood from animals has been performed manually or on an as necessary basis. Therein, the cannulized animal is anaesthetized and the sample is collected as required at intermittent time intervals with a syringe.
A system for automatic collection of small samples of blood from conscious animals has been described (Clark, R. G. et al, xe2x80x9cAutomated Repetitive Microsampling Of Blood: Growth Hormone Profiles In Conscious Male Rats,xe2x80x9d J. Endocr. (1986) Vol. 111, pp. 27-35). Therein rats bearing indwelling intravenous catheters were connected via swivels to a solenoid operated, three-way fitting and tubing to a multi-channel peristaltic pump, valves and a fraction collector. The tubing was filled with heparinized saline from a reservoir. Blood samples from the rats are drawn past the three-way fitting using a peristaltic pump. A small portion of the blood is pushed past the three-way fitting into a collector and the remainder of the sample is returned to the animal. This system, particularly, if the animal is small, fails to address the problem of a replacement substance for the animal""s blood that has been removed. The reference further fails to suggest a solution for the problem of contamination of the blood sample with saline solution or excess dilution of sample therewith.
There is now a need for an automated blood sampling system that can sample blood from a conscious animal and address the problems of replacement of sampled blood to maintain the animals metabolism. There is a further need to address the problem of contamination and excess dilution of the blood sample with heparinized saline solution. The present invention addresses and resolves the problems associated with the automatic blood sampling system described herein above.
The present invention is directed to an apparatus for automatically, repetitively sampling blood from a conscious animal, characterized as:
a) means for confining a conscious, catheterized animal;
b) a cannula having first and second ends, said first end connected to the catherized animal, said cannula being suitable for sampling blood from the animal;
c) a cannula valve having first and second ends, said first end connected to the cannula, said cannula valve opening and closing being computer controlled;
d) a cannula T-fitting having first, second and third ends, said first end connected to the second end of the cannula valve;
e) an outlet valve having first and second ends, said first end connected, via tubing, to the second end of the cannula T-fitting, said outlet valve opening and closing being computer controlled;
f) a dispensing tip having first and second ends, said first end connected to the second end of the outlet valve, said second end being suitable for discharging blood into a sample, collection vial;
g) means for horizontal and vertical movement of the dispensing tip, said means for movement being computer controlled;
h) an air T-fitting having first, second and third ends, said first end connected to the third end of the cannula T-fitting;
i) an air valve having first and second ends, said first end connected to the second end of the cannula T-fitting, said second end exposed to the check valve;
j) a syringe pump suitable for transferring blood and saline through the apparatus, said pump having first and second ends, said first end connected, via tubing, to the third end of the air T-fitting, said pump being computer controlled;
k) a rotary, programmable valve having four ports for receiving and discharging fluids, wherein the ports open and close by computer control, said first port being connected, via tubing, to the second end of the syringe pump;
l) a heparinized saline source, said saline source connected to the second port of the programmable valve;
m) a fraction collector, comprising:
i) a base having two horizontally, opposed, parallel tracks, and a single track horizontally positioned above and perpendicular to the horizontally opposed, parallel tracks,
ii) a temperature controlled rack in slidable contact with the horizontally opposed, parallel tracks,
iii) means for sliding the rack along the tracks, said means being computer controlled, and
iv) a plurality of sample, collection vials removably located in the rack, said vials being suitable for receiving samples from the dispensing tip; and
n) computer means for accepting timing commands for collecting samples from the animal in coordination with the opening and closing of valves, sliding of the temperature controlled rack, pumping of the syringe pump, and dispensing samples into the collection vials,
wherein samples can be collected at predetermined time intervals.
The invention is also directed to a process for automatically collecting samples from a conscious animal utilizing the apparatus described herein.